The ruling, issued by a three-judge panel on the San Francisco-based 9th Circuit Court of Appeals, means refugees and citizens of the seven majority-Muslim countries affected by the ban can continue entering the US as the ban makes its way through the court system.

"We hold that the Government has not shown a likelihood of success on the merits of its appeal, nor has it shown that failure to enter a stay would cause irreparable injury, and we therefore deny its emergency motion for a stay," the panel said in its ruling.

Shortly after the ruling was announced, Trump posted a defiant message to Twitter:

"SEE YOU IN COURT," Trump tweeted, foreshadowing a legal challenge that is likely to play out in the Supreme Court.

The Justice Department said it was reviewing the court's decision.

The ruling comes after a lower-court judge in Seattle, James Robart, issued a nationwide hold on the ban last Friday, prompting the US Justice Department to file an emergency stay. Robart's decision elicited a furious outburst from Trump, who called Robart a "so-called judge" and his opinion "ridiculous."

The executive order, signed by Trump on January 27, halted for four months all admissions of refugees into the US and froze for 90 days immigration from Iran, Iraq, Syria, Sudan, Somalia, Libya, and Yemen. Its hasty rollout caused chaos at airports across the world, leaving some refugees and visa holders stranded for hours.

Najmia Abdishakur (2nd L), a Somali national who was delayed entry to the US because of Trump's travel ban, is greeted by her mother Zahra Warsma (L) at Washington Dulles International Airport on February 6, 2017.REUTERS/Jonathan Ernst

Justice Department lawyer August Flentje argued on Tuesday that freezing Trump's order was an unlawful check on the president's authority over national-security decisions. Trump has maintained the order is necessary to defend the US from terrorism.

Lawsuits filed around the US, however, have accused the White House of unconstitutionally targeting Muslims — accusations buttressed by Trump's early campaign promise to temporarily bar Muslims from entering the US.

"We are a nation of laws," Washington Attorney General Bob Ferguson told reporters Thursday evening. "Those laws apply to everyone in our country, and that includes the president of the United States of America."

The three judges on the panel were Michelle Friedland, appointed by Barack Obama; William Canby Jr., appointed by Jimmy Carter; and Richard Clifton, appointed by George W. Bush.

Should Trump appeal to the Supreme Court, his prospects are unclear. The court's eight justices are split evenly in their ideological leanings, and a tie would leave the 9th Circuit ruling in place.